Telephone-exchange system



March 2 1926. 1,575,140

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14 5 s t 1March 2,1926. 1,575,140

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 1925 14Sheets-Sheet 2 b Amz S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM March 21926. 1,575,140

Filed March 31 1925 14 Sheets-Sheet 5 v March 2, 1926. 1,575,140

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14Sheets-Sheet 4 March 2 1926. 1,575,140

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 1925 l Sheets-Sheet5 M rh 2,1926. 1,575,140 S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM FiledMarch 51 19 25 l4 s 6 MarchZ 1926. 1,575,140

s. a. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14Sheets-Sheet 7 hue/7f? Jamue/ 15 W/Y/M/nS March 2 1926. 1,575,140

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 1925 1Sheets-Sheet 8 fnveman Jdmue/ 5 W/7ll'dms March 2 1926. 1,575,140

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14Sheets-Sheet l0 lnvenfoxt' Jamue/ 6i Will/am:

March 2 1926.

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM 14 Sheets-Sheet 11 Filed March31 1925 //2 van far. 1 fazmze/ 5! [WK/74m:

TELEPHONE EX CHANGE SYSTEM Filed March 31 1925 14 Sh five/277%. Jamue/fi140/0 10 March 2 1926.

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 I 1935 14 s t -st 15 MaQrch 2 1926.

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 I 1925 14Sheets-Sheet l4 :mx xx R mg $33G Patented Mar. 2, 192 6.

UNITED STATES 1,575,140 PATENT OFFICE.

SAMUEL B WILLIAMS, 0]? BROOKLYN, NEW YORK, ASSIGNOR, BY MESNE ASSIGN-HENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION 01 NEWYORK.

Original application filed September 26, 1923, Serial No. 664,825.Divided and this application filed. Match TELEPHONE-EXCHANGE SYSTEM.

31, 1925. Serial No. 19,577.

To all whom it may comer n:

Be it known that I, SAMUEL B. WILLIA us, a'citizen of the United Statesof America, residing at Brooklyn, in the county of Kings and State ofNew York, have invented certain new and useful Improvements inTelephone-Exchange Systems, of which the following is a fu 1, clear,concise, and exact description.

This invention relates in general to telephone exchange systems and moreparticularly to exchange systems of the class wherein automaticswitching apparatus is used for setting up conversational connections.

The principal object of the invention is a telephone system having animproved organization of recording and controlling equipment forexercising a quick and reliable controlover the selective switches.

A feature of the invention relates to the provision of means whereby theswitch controlling mechanism records the fact that a party line is beingcalled as soon as the line is reached to prepare for applying the properringing condition.

A further feature relates to an arrange ment whereby the controllingmechanism receives information from the recording device on a revertingcall and determines the selection of a special circuit for this purpose.

Other features and advantages of the invention will be more clearlyunderstood from the following detailed description and also from theappended claims.

This application is a division of application Serial No. 664,825, filedSeptember 26, 1923, issued as Patent No. 1,550,769, August 25, 1925.

Referring to the drawing, Figs. 1 to 13, inclusive, when arranged in theorder illustrated in Fig. 15, disclose an automatic telephone exchangesystem embodying the features of the present invention.

Fig. 1 illustrates a line switch of the coordinate type for' extendingsubscribers lines to trunks.

Fig. 2 shows one of the trunk circuits in full leading from the lineswitch to the first group selector.

Fig. 3 illustrates a portion of a number of first group selectorswitches of the coordinate type.

Fig. 4 illustrates one, if a number of co- Fig. 6 shows a senderselector switch of the coordinate type which serves to associate thetrunks with idle register senders.

Figs. 7 and 8 illustrate one of the record- 7 ing devices or registersenders as they will be termed hereinafter.

Fig. 9 shows a multicontact relay connecting device for associating theregister senders with the switch controlling mechanisms or markers.

Fig. 10 illustrates a controlling circuit arrangeinent common to anumber of the switch controlling markers. 7

Figs. 11, 12 and 13 discloses one of the switch controlling mechanismsor markers.

Fig. 14 is a schematic diagram of the system.

Fig. 15 is a diagram showing the manner 1n which the several sheets ofdrawing should be arranged.

The line switch 100, the selector and connector switches 300 and 400 andthe sender selector switch 600 are coordinate switches in which incomingcircuits are connected to outgoing circuits through the medium ofhorizontal links. The operating cont-acts are actuated by means ofcoordinate vertical and horizontal bars. For a clear undei standing ofthe construction and the operation of switches of this characterreference is made to the patent to S. B. Williams, No. 1,517,331, issuedDecember 2, 1924.

General arrangement of tlie system.

It is believed that a better understanding may be had of the system andof the features of invention embodied therein by first considering thegeneral plan illustrated in the diagram of Fig. 14. In this diagram thesubscribers lines, two of which, 1400 and 1401, are illustrated, enterthe exchange and terminate in vertical rows of contacts on the lineswitch 1402-. The line switch 1402 operating in response to theinitiation of the call extends the calling line over an idle trunk 1403to the first selector switch 1404. At the same time the trunk 1403 isextended through a sender selector switch 1405 to one of a plurality ofsenders 1406, 1407, etc.

The subscriber now manipulates his sending transmitter and stores u inthe selected sender, the record of the ca led snbscribers line.Thereafter, the sender through a connecting device 1408 is associatedwith one of two equivalent markers 1409 and 1410. The markers arearranged to be taken for use in alternation. If both are idle the marker1409 will be taken for use when a call arrives. Thereupon, the switchingdevice 1411 is adjusted to render the second marker1410 available forthe next call. If, while the second marker 1410 is in use, the firstmarker is released, the device 1411 will be readjusted so that the nextsucceeding call is handled by the first marker 1409. Should either ofthe markers become disabled for any reason, the switching device 1411.would throw the other marker into service permanently so that allincoming calls thereafter will be handled by the available marker untilsuch time as the disabled marker is restored to service.

Following the attachment of the sender to the marker as above outlined,the record of the called subscribers line is transferred from the senderinto the associated marker. The marker, thereupon determines theselection of the vertical row of contacts which represents the group ofcalled subscribers? lines containing the desired line. These calledsubscribers lines appear in a number of coordinate connector switches1418, 1414, etc. and each such switch accommodates a plurality of thegroups of lines. Therefore, it is necessary for the marker not only todetermine which of the connectors shall be taken for use, but also todetermine the particular vertical group of contacts in that connector inwhich appears the called line. Having fixed the vertical row of contactscontaining the called line in the connector switch 1413, the markerdetermines the selection of a group of trunks 1412 outgoing fronrtheswitch 1404 and terminating in the switch 1413.

Following this the marker determines the selection of an idle trunk inthe group 1412 andalso determines an idle horizontal link in each of theswitches 1404 and 1413 and then operates the horizontalmagnets to eX-tend the calling line through the switches to the calledsubscribersline. Upon the completion of the connection the marker is released andimmediately thereafter the register sender is also disconnected.

Should the calling subscriber desire connection with a party line themarker is arranged to receive information as soon as connection hasprogressed to a point where the called line is ascertained in theconnector switch. This information in the marker is then transferredthrough the first selector switch 1404 to the trunk circuit incomingfrom the line switch 1402 where it serves to determine the selection ofthe proper code of ringing current to be applied to the party line. Aswill be seen hereinafter for four. party- 'lines a semi' see lectiveringingarrangement is employed in the present system. Each party linehas four appearances in the connector switch, two of whichare reversedas regards the tip and ring conductors. The ringing equipment in thetrunk circuit is adapted to apply a code consisting of either one ringor two rings with the usual intervening intervals. By selecting one oftwo dilierent codes by use of the marker and by reversing the'tip andring conductors of the connector switch terminals, two bellson the partyline may be rung at a time either with one shortring or with two shortrings. The parties at these two substations will differentiatetheirbells by means ofthe codes.

7 In the event that the subscriber on aparty line wishes to make areverting call,'namely, one to another substationon the same line, themarker receives special information from the recording sender. By theuse of this information the marker determines the operation of the firstselector switch 1404 to select one of a number of special'trunks 1415,each including a reverting ringing equipment 1416. In this case theconnector switch 1413 is dispensed with entirely. Having selected areverting ringing equipment 1416, the proper ringing condition isascertained from the marker and is applied to the party line to ringboth the called and calling subscribers bells.

Detailed description of establishment of a connection.

Local ofiice caZZ.It will first. be considered that the subscriber ofline 101 wishes to converse with another subscriber whose call numberis2 1 3 2.

\Vhen the calling subscriber removes'his receiver from the switchhook'acircuit is closed from battery, throughthe winding of relay 102, outerback contact of relay 103, through the subscribers loop, inner backcontact of relay 103 to ground. Relay 102 operates and closes a circuitfrombattery through relay 104, left back contact of relay 105, conductor106, outer contact of relay 102, conductor 107 to ground. Relays 104,105 and 108 enclosed'within the broken rectangle pertainlto theverticalgroup of lines in the row 110 of switch100. These relays arebrought into action whenever one of the linesof the corresponding groupinitiates a call.

Relay 104 now'closes a circuit from battery through the left-handwinding of relay 108, right front contact of relay 104, left backcontact ot relay 1'09'to ground at the outer left back contact of relay111. Relay 108 energizes and looks over its inner right front contact,winding of relay 109 to ground at relay 111. Relay 109 energizes andcloses an obvious circuit for slow release relay 125. Relay 109 alsocloses a circuit from battery through the vertical operating magnet 113,outer right front contact of relay 108, left front contact of relay 109to ground at relay 111.

Relay 108 closes a circuit for relay 105, which energizes. Relay 112 wasoperated over the left front contact of relay 104, couductor 107 toground. Relay 105 now opens the circuit for relay 104 which releases andopens the operating circuit for relay 112, but this circuit waspreviously replaced by a multiple path over the left front contact ofrelay 105 and outer front contact of relay 102. Relay 112 closes aholding ground for relay 105.

Relay 109 also closes a circuit from battery through vertical operatingmagnet 114, terminal and switch arm 116 of allotter switch 115, backcontact of relay 119, right contact of relay 111 to ground at outerright front contact of relay 109. The allotter switch 115 has a positionfor each of the several trunks which lead out from the line The allotterswitch 115 is operated by magnet 118 and will always take a position ofrest corresponding to an idle trunk. Switch 115 is assumed to have beenpreviously operated to find the idle trunk 121. Consequently, verticaloperating magnet 114 is now operated and locks itself over the windingof relay 111 to ground at relay 109. -Relay 111 being shunted at thistlme does not operate.

The magnets 113 and 114 operate and prepare the contacts in verticalrows 110 and 120, respectively. Magnet 114 closes a circuit which may betracedv from battery through the winding of relay 602, left backcontacts of relays 202 and 203, conductor 124 to ground at magnet 114.Relay 602 operates and at this time starts a series of operations in thecircuit provided for the sender selector 600 in a manner similar to Theoperations described for the line switch 100. Magnet 114 also closes acircuit traceable from battery, winding of relay 119, contact andwinding of stepping magnet 118, switch arm'117 and test-terminal ofswitch 115, conductor 124 to ground at magnet 114. Relay 119 is slow torelease and keeps the circuit for switch arm 116 open during thestepping operation of switch 115. Magnet 118, in operating the switch115, opens and closes its I own circuit and advances the brushes 116 and117 to a test-terminal to which no ground is applied by a verticaloperating magnet or otherwise. Relay 119, in operating, opens the shuntaround the winding of relay 111. Relay 111, therefore, operates inseries with the winding of magnet 114. Relay 111 opens the circuit forrelay '125 which is made slow to release in order to permit certainoperations to take place before its armature is completely retracted.

When magnet 113 operated it closed a circuit which may be traced frombattery, right-hand winding of relay 126, inner left front contact ofrelay 102, conductor 127, outer left contact of relay 108, contact ofrelay 128 to ground at magnet 113. Relay 126 common to a group ofhorizontal operating magnets 144, 132, any one of which is able toconnect the calling line to an outgoing trunk. With each horizontaloperating magnet is associated a relay 133, 134 which will cause anincoming call to be extended to an idle. link in the line switch 100. Itwill be assumed that the first link 130 of the group associated with thecalling line is idle. Relay 126, in operating, closes a locklng circuitfor itself through the winding of relay 128 to ground at magnet 113.Relay 128 operates in this circuit. Relay 126 now extends a circuit forhorizontal operating magnet 144 which may be traced from battery throughthe right-hand winding of magnet 144, left back contact of relay 133,right front contact of relay 126, front contact of relay 128 to groundat relay 111, when relay 111 operates as above described. Horizontaloperating magnet 144 now operates and causes the connection to beestablished between the link 130 and a set of contacts in vertical row110 and also with a set of contacts in vertical row 120. The subscribersline is thereby extended through to the trunk 121.

Ground at magnet 114 now is extended through the winding ofrelay 131,conductor 134, contact in vertical row 120 and wire of link 130, throughthe right winding of relay 133, both windings in series of magnet 144 tobattery, thus providing a holding circuit for magnet 144. The ground atmagnet 114 is alsoextended from the wire of link 130, through contact invertical row 110 and through the winding of cut-off relay 103 which nowoperates. Relay 102 deenergizes and causes the release of relay 112,provided that no other call is waiting.

Relay 602 in operating closed a locking circuit for itself over itsouter right contact, conductor 236 to ground at the inner back contactof relay 204. Relay 602 also connects ground to conductor 235 throughrelay 203 to battery. Relay 203 energizes and connects ground at itsleft front contact to conductor 124. The complete release of re lay 125can now take place and will cause the release of magnet 113, which inturn, opens the holding circuit for relays 128 and 126 which bothrelease. Relay 125 also opens the holding circuit for relays 109 and108. The release of relay 108 next causes the release of relay 105. Therelease of relay 109 opens the holding circuit for relay 111 and magnet11 1. The releaseof relay 128 opens the operating circuit for horizontalmagnet 14 1 which now holds up through the wmd- 'ing of relay 183 aspreviously traced to ground on conductor 12 1. The shunt is now removedfrom the operating winding of relay .33 and this relay energizes and inso doing shifts the operating circuit for mag net 1 14; onto magnet 132,which now will be ready to take the next call in ithesamc horizontalgroup. lVith the magnets 113 and 111 deenergized and the allotter switch115 at rest the line switch 100 is in readiness .to extend another call.

Turning now to the operation of the sender selector 600, the operationof relay 602 closes circuits for relays 60%, 605, 608 and (309, in thesame manner as described for relay 102 in the line switch circuit.Vertical magnet 613 is operated over a circuit from battery through itsown winding, outer right front contact of relay (308, left front contactof relay 609 to ground at relay 611. Vertical magnet 61d is operatedfrom battery through its own winding, terminal and brush arm of theallotter switch (315, contacts of relays 619 and 611 to ground at relay(509. Vertical magnet 613 connects ground to horizontal group relay(326, which operates and locks in series with relay 628 and theoperation of the horizontal magnet 631 takes place as soon as relay(5'11 energizes inthe holding circuit for magnet e14. The verticalmagnet tila connects ground to the test bank of allotter switch 615which will step forward to the set-of terminals corresponding to thenext idle vertical operating magnet. Relay 625 energized atthe timerelay 609 was energized and its release was subsequently started whenrelay G11 operated. Belay 625 is slow to release inorder to provide timefor certain operations to take place before its complete release.

lVith horizontal magnet 631 and vertical magnets 613 and '614 operated,contacts m vertical rows 610 and 620 will now close with the wires inhorizontal link 6330 and the connection is thus established between thecircuit of trunk 121 and the sender shown in Figs. 7 and 8. Ground frommagnet 61-; is extended to hold horizontal magnet 681 in a mannersimilar to that described for magnet 1 A of line switch 100.

The ground at the right contacts of magnet 61 1 is also connected bymeans of a contact in vertical row 610, conductor'23d, winding of relay20 1 to battery. Relay-201 energizes and connects the subscribers loopthrough the scndcrselect-or 600 to the sender circuit in Fig. 7. Acircuit is now completed from battery through the left winding of relay700, outer left contact of relay 715, conductor 653, contacts and wireof link 630, conductor 283, lower :front contact of relay 20%, conductor123, contacts and wire of link 1300f line switch 100, conductor 143,subscriber?s loop, conductor 142, contacts and wire of link 130,conductor 122, upper front contact of relay 204., conductor 232,contacts and wire of linlc630, conductor 652, inner left contact ofrelay 715, left winding of coil 713 to ground at relay 714. Relay 700operates in this circuit and'connects ground to relay 709. ielay 7 09,in turn, operates relay. 710 and a holding ground is now extended fromthe second outer front contact of relay" 710 to conductor (324.Slow-torelease relay 625 can now complete its [release and the releaseof vertical magnets (513 and 611- of thesender selector will take placein a manner similar to the release of the vertical magnets ofthe line.switch 100 as described above. Horizontal magnet 631 will be heldenergized by the holding ground just described on .conductor 624. Ttelay602 was ireleased at the time relay 20 1 operated and the rclease. ofthe remaining relays related'to thesenderselector willtake place asdescribed above for similar relays-associated with the line switch 100,so that thesender selector 600 will again be in a position to extend aconnection from another trunk to another sender.

The operations so far described were caused by the removal from theswitchhook of'the subscribers receiver. At the time relay 7 1O operateda circuit was completed from ground at its innermost front contact,conductor. 7 30, through the right winding of coil 713, conductor 758,outer left back contactof'relay 861 to a-source of dial tone. This toneis transferred by induction from the right to the left windingyof coil713, and may thus be heard by the subscriber who then will set his dialfor the sending of the first digit. The circuit is in a condition toreceive the lirstseries of :two impulses.

The first break in the line circuit causes relay 700 to release and openashort circuit across the right winding of relay 7-11 which will operatein a circuit from battery, through coil 716, right winding of relay 711and right front contact of relay 7 O9. Relay 711 energizes and operatesrelay 712 which locks over its inner left contact to conductor 730 whichis grounded atrelay 710. The complete operation of relay 712 is insuredby the locking of relay 711 over the outer left back contact of relay712 to grounded conductor 7 30. Relay 717 was operated over a circuitfrom battery through the winding of relay 717, left back contact ofrelay 718, inner right back contact of relay 719 to ground on conductor7 30. Another circuit is now closed from battery through the winding ofrelay 717, middle left contact of relay 711 to grounded conductor 730. Acircuit is also closed from battery through the winding ofrelay 7 18,outer left-contact of relay 711 to conductor 730. Relay 718 groundedconductor .730.

energizes and looks over its inner left contact and inner right contactof relay 719 to conductor 730. Relay 712, in operating, ex-

tends a circuit from ground at right contact of relay 711, over theright contact of relay 712, left middle back contacts of relays 7 04:703, 702 and 701, winding of relay 701, outer left back contact of relay7 02 to the holding conductor 750, outer right contact of relay 719,outer left contact of relay 711 to The winding of relay 701 is thusshort circuited.

When the line circuit is again completed relay 700 energizes and againshunts the operating winding of relay 711 which, therefore, releases,its holding circuit having been opened by the operation of relay 712.The ground at right contact of relay 711 is thereby removed from thecircuit described for relay 701, which circuit now includes the rightwinding of relay 712 and battery. The first counting relay 701 thereforeoperates and locks itself to battery over its inner left contact, andthereby places a shunt around relay 712 Relay 712 is differentiallywound and the current in the right-hand winding is now so much reducedthat the relay will release, the release being accelerated by theleft-hand winding. It will be noted that relays 709 and 717 are slow torelease and, therefore, are maintained energized during the reception ofimpulses. Upon the second break in the line circuit relay 700 againdeenergizes. Relays 711 and 712 again energize as just dc, scribed.Ground from the right contact of relay 711 is now extended over theright contact of relay 712, middle left back contacts of relays 704, 703and 702, middle left front contact of relay 701 through the winding ofrelay 702, outer left contact of relay 703 to the holding conductor 750.The second counting relay is now shunted and upon closure of thesubscribers line, relay 700 again energizes, relay 711 dee energizes andrelay 702 will energize in series with the right winding of relay 712.Relay 702 locks to battery and shunts the windin of relay 712 whichagain releases. Relay 02 also opens the holding circuit for relay 701 atits outer left front contact and relay 701 releases. It should be notedthat the inner left contacts of the counting relays 701 to 706 are madeto close slightly before the middle left front contacts open so that theholding circuits for these relays are sure to be closed before theiroperating circuits are opened.

The first series of impulses now having been completed an intervaloccurs, during which slow-to-release relay 717 will have time tocompletely release Ground is thereby extended from conductor 730 overthe contact of relay 717, outer left contact of relay 718, left contactof relay 719, conductor 751, right back contact of relay 812, winding ofrelay 811 to battery. Relay 811 energizes and looks over its lower frontcon tact to conductor 752, through winding of relay 719, left outercontact of relay 718, contact of relay 717 to grounded conductor 7 30.Relay 719 does not operate in this circuit, being shunted by thepreviously described circuit. Relay 811 in energizing establishes aconnection at its upper front contacts from the counting relays to therelays Th. in the thousands register over conductors 721, 722, 723 and724. For the present setting of the counting relays 'a ground will beextended from the grounded conductor 750, over the outer left frontcontact of relay 702, conductor 722, contact of relay. 811, winding ofrelay B of the thousands register Th. to battery. Relay B locks toconductor 830which is grounded at relay 710. Relay B further closes acircuit from conductor 880, outer left contact of relay B, through thewinding of relay 812 to battery,'causing relay 812 to operate and lookover its inner left contact, back contact of relay 862 to conductor 830.Relay 812 closes a circuit for relay 861 which now removes the dial tonefrom the line circuit and prepares a circuit for the application of busytone Relay 812 also opens the energizing circuit for relay 811 and thusremoves the short around relay 719 which therefore operates. Relay 719opens the holding circuit of the counting relays at its outer rightcontact and at its right inner contact relay .719 opens the holdingcircuit of relay 718.

The counting relay 702 releases and also relay 718, which in turn, opensthe circuit for relays 719 and 811 at its outer left contact and relays719 and 811 release.

Slow-to-release relay 717 now again energizes over the left back contactof relay 718 and the setting of the thousands register is thuscompleted.

The operation of this circuit in receiving the. second digit is similarto that for the first digit as described above, but since only oneimpulse is sent out, relay 701 will remain energized at the time slowrelease re.- lay 717 completes its release in the time interval betweenthe second and third digit. Relay 717 now extends the ground fromconductor 730, over its own contact, left outer contact of relay 718,left contact of relay 719, conductor 751, right front contact of relay812, right back contact of relay 822, through the winding of relay 821to battery. Relay 821 connects the counting relays to the H relays inthe hundreds register and locks itself to conductor 752, through windingof relay 719, contact of relays 718 and 717 to conductor 730. Relay 719is again shunted as described above. A circuit is now extended fromconductor 7 50,

ergize.

inner right front contact of relay 7 01', right and 821 release and,slow release relay 717 energizesas described for the first digit.

The setting of the hundreds'register is thus completed and the circuitis ready to receive" the third digit which, in this case, 18' assumed toconsist-of tl'iree'nnpulses. Theoperations for the first two pulses willbe the same as for the first-digit. Atthe'end' of the third impulse whenrelay 7 11 deenergizes and the shunt'is removed from relay 703, thisrelay energizes over acircuit traced from battery, right winding andright front contact of relay 712, middle left back cont-act of relays704: and 708, middle left front contact of relay 702, winding of relay703, outer left contact of relay 7043 to ground at conductor 750. Relay703 operates and opens the circuit for relay 702 and in locl'ring placesashunt around the winding of relay 712 which deenergizes as previouslydescribed. heir now slow-torelease relay 717 completes its release,

ground from conductor 7 30*is extended-over its own contact, outer leftfront contact of relay 718, left contact of relay 7'19, conductor 751,right front contact of relays 812 and 822 and right back contact ofrelay 832, through the winding of relay 831 to battery. This circuitalso extends f-romthe right back contact of relay 832, through windingof relay 863. These two relays en- Relay 8'63 temporarily removes groundfrom its armature for purposes as will be described later. Relay 831, inoperating, connects the counting relaysto the relays T of the tensregister and two circuits arenow extended by thecounting relay 7 03,from the conductor 750', one to be traced over itsouter left frontcontact, conductor 722, contact of relay 831, winding of relay B tobattery. The other circuit "is closed at the right front contact ofrelay 703, conductor 721, contact of relay 831, through winding of relayA to battery. Relays A and 'B operate; locksdirectly to conductor 830,while A Relay B locks over itsinner'l'ef't front contact innerrighflbackcontact of'rel'ay 864C to conductorSBO. Relay- 832 isnow operated andlocked by the operation of relays A and B; The operating circuit forrelays 831 and 863 is. opened and the shunt removed from relay 719; Thesubsequent release of relays7l8, 719 and 831 takes place as throughgrounded conductor 1010.

previously described and slow-to-release relay 71'7 again energizes.

The circuit isnow ready to receive the units digit, which in the caseassumed, consists of'two impulses. The operations in re- ,sponse tothese two impulses are the same as described for the firt digit and whenrelay 717 releases, a circuit is extended from conductor 730, contact ofrelays 717, 718and 719, conductor 7 51, right front contacts of relays812, 822, 832, right back contact of relay 842, winding of relay 84:1 tobattery. Relay 841 now connects the counting relays to the relays U intheunits registerand the circuit from the second counting relay 702 willbe extended through the winding of relay B which locks and furthermoreoperates the relay 842. This latter relay also locks and opens the shuntaround the winding of relay 719 which operates. The operation of relay719 and the subsequent release of relays 718, 719 and 8 11 take place,whereuponrelay 717 energizes.

\Vhen relay 84-2 operated a circuit was completed from battery leftwinding of relay 731, conductor 732, outer left front contact of relay812, inner left back contact of relay 80-1 to ground at contact of relay863'. Relay 731 energizes and locks over its own right contact, innerleft back contact of relay 718, inner right back contact of relay 719 toconductor 730. Ground is now extended from the inner left front contactof relay 73 middle left contacts of relays 733 and 73 1, outer rightback contact of relay 7 35, left back contact of relay 736, conductor901, through relay 91 1 to battery. Rel-(13 911 energizes and closesacircuit from battery through winding of relay 921, right back contactof relay 922, lower front contact of relay 911-, conductor 925, throughrelay 1001 to ground. Relay 921 operates in this circuit and locks atits left front contact over back contacts of relays 1003 and 1002,though the winding of relay 1001 to, ground. A circuit is newcomplctedfor the lower winding of relay 912 from battery over the upper frontcontact of relay 9'11, upper back contact of relay 914", right frontcontact of relay 921, Relay 912 energizes and extends ground to relay922 which energizes and closes a holding circuit. for itself at itsinner left contact, over cont'acts'of relays 923 andf924c'providcd relay924 is operated. Relay 922 also closes a holding circuit for relay 912from battery over the upper front contact of relay 912, back contact ofrelay 915,.left front contact of relay 922,. winding of relay 1003 togrounded conductor'1010. Relay 1003 operates in'this circuit and indoing so counects ground from conductor 1010 over the upper frontcontact of relay 912, to the Winding of multicontact relay 913. Relay

